A multiplicity of wireless base stations is installed to enable communications to be performed anywhere in a wireless communication network for mobile phone services etc. The wireless base stations are classified into: an outdoor base station installed on a roof floor of a building or at a steel tower to cover a communication area (macro cell) spreading several kilometers in radius; and a micro base station installed in a small-sized shop or a general house to cover a communication area (femto cell) spreading several tens of meters in radius.
The outdoor base station is also called a macro base station and a macro cell base station. The micro base station is also called a femto base station, a femto cell base station, femto and a femto cell.
Over the recent years, a wireless communication system such as a mobile communication network has broadly examined an improvement of a quality of indoor mobile phone services and an expansion of a service area by setting up the femto base station in an indoor space of a general home or an office.
The wireless base station in the existing mobile communication network including the femto base station transmits a common pilot signal to a mobile station. The mobile station receives this common pilot signal, thereby establishing synchronization with the wireless base station and performing channel estimation. The mobile station attains data transmission and data reception with respect to the wireless base station connected to the self-device.
FIG. 1 is a diagram illustrating an example of common pilot channel power and data channel power of a downlink transmission channel. Herein, in a LTE (Long Term Evolution) system based on 3GPP (Third Generation Partnership Project) Standards, the data channel power of the downlink transmission channel is, as illustrated in FIG. 1, defined by the common pilot channel power and a power offset with respect to the common pilot channel power.
To be specific, in the LTE system, the data channel (PDSCH (Physical Downlink Shared Channel)) power of the downlink transmission channel is determined as a total value of transmission power of a Reference Signal (RS Power) corresponding to the common pilot signal and a power offset (p-a) with respect to the transmission power. Therefore, a change of the transmission power of the PDSCH is actually attained by adjusting a set value of the “RS Power” and a set value of the “p-a”.
The downlink transmission channel is defined as a transmission channel in a direction from the wireless base station toward the mobile station.